1. Field of the Invention
The present invention relates to a coated cutting tool comprising a body coated combining a multi textured alpha-alumina (α-Al2O3) layer, the method of making and use the same. The layer is grown by chemical vapour deposition (CVD) and the invention provides an oxide layer with improved wear properties and good chip forming machining properties.
2. Description of the Related Art
Typically, CVD alumina based coatings comprise an inner layer of titanium carbonitride and an outer layer of Al2O3. The development and use comprise different Al2O3 polymorphs, e.g., α-Al2O3, κ-Al2O3 and γ-Al2O3 as well as multilayer structures thereof.
U.S. Pat. No. 3,967,035 discloses an α-Al2O3 coated cutting tool insert where the layer is bonded to the insert through a thin intermediate layer of an iron group metal aluminate.
U.S. Pat. No. 3,836,392 discloses an α-Al2O3 coated cutting tool insert where the layer is deposited directly onto the insert.
U.S. Pat. No. 3,837,896 discloses an α-Al2O3 coated cutting tool insert where an intermediate carbide or nitride layer is deposited prior to the oxide layer.
U.S. Pat. No. 4,619,866 discloses an α-Al2O3 coated cutting tool insert where the oxide is deposited utilizing a dopant selected from the group consisting of sulphur, selenium, tellurium, phosphorous, arsenic, antimony, bismuth and mixtures thereof, dramatically increasing the growth rate of the layer.
U.S. Pat. No. 5,968,595 discloses a cutting tool insert coated with single- or multilayers, comprising at least one layer of a {210} textured κ-Al2O3.
U.S. Pat. No. 5,162,147 discloses a cutting tool insert coated with an inner α-Al2O3 layer and an outer κ-Al2O3 layer.
U.S. Pat. No. 5,700,569 discloses a multilayer oxide coated cutting tool insert comprising layers of either α-Al2O3 or κ-Al2O3.
U.S. Pat. No. 6,015,614 discloses a cutting tool insert coated with a multilayer structure of TiN/TiC on a thick layer of a single and/or bi-layer of α-Al2O3 and κ-Al2O3.
U.S. Pat. No. 6,632,514 discloses a cutting tool insert coated with a multilayer of κ-Al2O3 and TiN or Ti(C,N) layers.
U.S. Pat. No. 7,470,296 discloses a cutting tool insert coated with a multilayer comprising layers of Ti(C,N) and Al2O3, preferably κ-Al2O3.
U.S. Pat. No. 6,855,413 discloses a cutting tool insert coated multilayer comprising layers of TiN and κ-Al2O3.
U.S. Pat. No. 6,572,991 discloses an oxide coated cutting tool insert with an outer layer a layer of γ-Al2O3.
U.S. Pat. No. 6,689,450 discloses a coated cutting tool insert having a multilayer of κ-Al2O3 and or γ-Al2O3 or TiN.
Further enhancement of the oxide layers has recently been achieved through the control of crystallographic orientation, texture, especially for the α-Al2O3 polymorph. This has been achieved by the development of new synthesis routes comprising the use of nucleation and growth sequences, bonding layers, sequencing of the reactant gases, addition of texture modifying agents and/or by using alumina conversion layers. Commonly, the texture is evaluated by the use of X-ray diffraction (XRD) techniques and the concept of texture coefficients.
Textured Alumina Layer Synthesis Using Various Bonding/Nucleation Layers and Growth Sequences
U.S. Pat. No. 7,094,447 discloses a method to produce textured α-Al2O3 layers with improved wear resistance and toughness. The α-Al2O3 layer is formed on a (Ti,Al)(C,O,N) bonding layer using a nucleation sequence composed of aluminizing and oxidization steps. The layer is characterized by a {012} growth texture as determined by XRD.
U.S. Pat. No. 7,442,431 discloses a method to produce textured α-Al2O3 layers on a (Ti,Al)(C,O,N) bonding layer using a nucleation sequence composed of short pulses and purges of Ti-containing pulses and oxidizing pulses. The layer is characterized by a {110} growth texture as determined by XRD.
U.S. Pat. No. 7,455,900 discloses a method to produce textured α-Al2O3 layers on a (Ti,Al)(C,O,N) bonding layer using a nucleation sequence composed of short pulses and purges consisting of Ti+Al pulses and oxidizing pulses. The layer is characterized by a {116} growth texture as determined by XRD.
U.S. Pat. No. 7,442,432 discloses a method to produce textured α-Al2O3 layers on a (Ti,Al)(C,O,N) bonding layer with a modified but similar technique as disclosed in U.S. Pat. No. 7,455,900. The layer is characterized by a {104} growth texture as determined by XRD.
US 2007104945 discloses a textured α-Al2O3 coated cutting tool insert for which a nucleation controlled α-Al2O3 layer texture is obtained. The layer is characterized by a {006} growth texture as determined by XRD.
US 2008187774 discloses a texture-hardened α-Al2O3 coated cutting tool insert with a {006} growth texture as determined by XRD.
U.S. Pat. No. 6,333,103 discloses a textured α-Al2O3 layer grown on a Ti(C,O) bonding layer characterized by a {10(10)} growth texture as determined by XRD.
Textured Alumina Layer Synthesis Using Sequencing of Reactant Gases
U.S. Pat. No. 5,654,035 discloses a body coated with refractory single- or multilayers, wherein specific layers are characterized by a controlled microstructure and phase composition with crystal planes grown in a preferential direction with respect to the surface of the coated body (growth texture). The textured α-Al2O3 layer is obtained by sequencing of the reactant gases in the following order: CO2, CO and AlCl3. The layer is characterized by a {012} growth texture as determined by XRD.
U.S. Pat. No. 5,766,782 discloses a cutting tool coated with refractory single- or multilayers including α-Al2O3, wherein specific layers are characterized by a controlled growth texture with respect to the surface of the coated body. The textured α-Al2O3 layer is obtained by sequencing of the reactant gases such that first CO2 and CO are supplied to the reactor in an N2 and/or Ar atmosphere followed by supplying H2 and AlCl3 to the reactor. The layer is characterized by a {104} growth texture as determined by XRD.
Textured Alumina Layer Synthesis Using Texture Modifying Agents
U.S. Pat. No. 7,011,867 discloses a coated cutting tool comprising one or more layers of refractory compounds out of which at least one layer is an α-Al2O3 layer having a columnar grain-structure and a {300} growth texture as determined by XRD. The microstructure and texture is obtained by adding ZrCl4 as a texture modifying agent to the reaction gas during growth.
U.S. Pat. No. 5,980,988 discloses a {110} textured α-Al2O3 layer as obtained by using SF6 as a texture modifying agent during growth. The texture is determined by XRD.
U.S. Pat. No. 5,702,808 discloses a {110} textured α-Al2O3 layer as obtained sequencing SF6 and H2S during growth. The texture is determined by XRD.
Textured Alumina Layer Synthesis Using Conversion Layers
US RE41111 discloses a {0001} textured α-Al2O3 layer as obtained using an initial heat treated alumina core layer (conversion layer) with a thickness of 20-200 nm. The texture is determined by electron back scattering diffraction (EBSD).
An explanation of EBSD and the analysis for texture evaluation by using pole figures, pole plots, orientation distribution functions (ODFs) and texture indexes can for instance be found in Introduction to Texture Analysis: Macrotexture, Microtexture, and Orientation Mapping, Valerie Randle and Olaf Engler, (ISBN 90-5699-224-4) pp. 13-40.